In "High-Rise," based on the 1975 novel by J.G. Ballard, Sienna Miller plays Charl|Magnolia Pictures

Sienna Miller can’t believe “High-Rise” exists either. Based on J.G. Ballard’s dystopian 1975 novel, the film concerns a tricked-out apartment complex that falls into disrepair — and its inhabitants along with it. It’s as mad and decadent as the source, and with its all-star cast engaging in wild parties and orgies and warfare and the occasional dog-eating, it seems beamed from another, less blockbuster-besotted era.

“I really didn’t think anyone made films like this anymore,” the English actress tells us. As it happens, this is exactly the type of movie the actress wants to make. Not that she’s against the superhero films that clog multiplexes.

“They’re fun and they’re entertaining, some of them. But the art is gradually being filtered out. That’s why TV is becoming more artistic,” she says. But she thinks there’s a place for art in movies like this. “They’re thought-provoking. They don’t spoonfeed the audience. They allow you to have opinions. It’s not manipulative filmmaking. It leaves you with questions. I think that’s what cinema should be.”

This is all according to plan. A few years ago, Miller, now 34, decided to reinvent herself. Gone, she hoped, would be her past as just another model-actress, as well as the tabloid-friendly on-off partner of Jude Law. Instead she’s tried to align herself with auteur directors and daring projects.

It’s worked: In addition to supporting roles in “Foxcatcher” and “Mississippi Grind” — plus James Gray’s “The Lost City of Z” and Ben Affleck’s “Live by Night” en route — she scored the co-lead in Clint Eastwood’s “American Sniper,” the highest-grossing release of 2014.

Still, Miller treads lightly. Speaking about “High-Rise,” she’s loath to lump herself in with her famous co-stars, including Tom Hiddleston, Luke Evans, Elisabeth Moss and Jeremy Irons. “I don’t really have that following,” she claims. When she speaks, softly but assuredly, you believe she means it.

“High-Rise” has famously spent decades in development hell; it was even too difficult for Nicolas Roeg (“The Man Who Fell to Earth”), who wanted to film it in the 1970s. Ballard’s classic has long been lumped in with all the other great, unfilmable novels, until director Ben Wheatley and his screenwriter/wife Amy Jump took a whack at it.

“I think the script really manages to capture the essence of the book,” Miller says. One of Ballard’s bigger claims to fame is writing books that wound up becoming true: “The Drowned World,” from 1962, foresaw global warming; 1970’s “The Atrocity Exhibition” imagined a future in which Ronald Reagan became president. “High-Rise”’s prophecy is more nebulous: It shows what happens when society becomes too used to comforts. When that falls apart, people become feral and turn to tribalism. In other words, it’s the Internet. Miller is grim about social media.

“The effect it’s having on our species is far more sinister than we’re allowing. The feeling of being validated by ‘likes’ and having followers — the whole thing is really scary. You get narcissism, self-obsession, self-promotion — these very base, animalistic aspects that can lead to eating a dog,” she says, jokingly referring to an increasingly common pastime in “High-Rise.”

Miller doesn’t take part in that section of modern living. “I like the idea of seeing what all my friends are up to,” she explains. “But I just don’t want to engage with that many people. I don’t have that desire to feel slightly exposed in a way that doesn’t make me feel good. At the same time that’s probably completely stupid in terms of my ability to have worth and market value. My agent, I’m sure, thinks it would be useful. But it’s just not for me.”

Watching the movie, with its darkly funny and often harrowing barrage of excesses, it’s impossible to imagine filming it. But Wheatley — of the brutal “Kill List” and the pitch black comedy “Sightseers,” about a murderous couple on holiday — knew what he was doing.

“It was controlled chaos. What was exciting for me was there were no boundaries in terms of what you could do,” she recalls. “There were moments that were really complicated and hard,” she says, referring to one scene where her character — the more detached and vulnerable Charlotte — is violated by a documentary filmmaker played by Luke Evans. “That was not pleasant. And some of the more romantic scenes are excruciatingly embarrassing, though necessary to the plot.”

And yet it was all worth it for a film that felt artistically freeing. “It felt like old school filmmaking: ‘Let’s be a group, let’s be a troupe. Let’s get together and be artists,’” she says. “It’s not like, ‘Let’s make money.’ It’s like, ‘Who gives a shit what the film makes? Let’s have a great time and make a film people will respond to.’”